The present invention relates to a stator of an electrical machine having a plurality of coils which are connected to one another on one side of the stator. The present invention also relates to a corresponding method for connection of a stator.
In the case of motors using pole coil technology, the winding ends must be connected to one another. This connection can be automated only with difficulty because of the highly flexible lacquered copper wires which are normally used for the motor coils.
Until now, the connection process has been carried out by manually twisting and welding or soldering the winding ends. A so-called circuit mount, into which the wires are inserted, is frequently used as insulation between the phases in the area of the winding ends. This makes it possible to dispense with special flexible insulating tubes.
Known alternatives to this are, for example, connection by means of a printed circuit board. However, connection such as this has the disadvantage of the reduced withstand voltage, the reduced current carrying capability and the reduced resistance to temperature. Furthermore, it is known for the connection to be made on a coated plastic mount using insulation-displacement terminal technology. However, insulation-displacement terminal technology has the disadvantage that only a restricted current can flow through the connections, because of the relatively high contact resistance.
The book B{hacek over (a)}l{hacek over (a)}, C., Fetita, Al., Lefter V.: Handbuch der Wickeltechnik elektrischer Maschinen. [Winding Technology Manual for Electrical Machines] 2nd Edition Berlin, Verlag Technik, 1976, pages 292-301, discloses switching connections for connection of coil groups or of multiple coils. In the case of winding wires, these connections are produced by twisting and welding. In large machines, the connections composed of bars are bent and insulated, and solder sleeves are expedient for the connection in this case. Welding is suitable for the connection of wire ends. In particular, two wires which are cut off at right angles can be connected to one another by cold-pressure welding. In this case, the wires are pressed against one another with a butt joint by means of an apparatus, in such a way that the material is pinched all round the pressing point.
Furthermore, the document DE 103 28 720 A1 describes a connection element for a winding of an electrical machine, which has an annular mount composed of an insulating material, and conductor tracks arranged in the mount, for electrical connection of the coils and winding sections. For low-cost fabrication of a compact, physically small connection element, the conductor tracks are formed by sheet-metal parts which are inserted into the annular mount upright or staggered radially one behind the other, and offset with respect to one another in the circumferential direction. All the coil starts and coil ends are connected to contact lugs on the sheet-metal parts in a welding or soldering process.